diff --git a/tests/server/request_handlers/test_default_request_handler.py b/tests/server/request_handlers/test_default_request_handler.py
index d440cf2f..6cb21662 100644
--- a/tests/server/request_handlers/test_default_request_handler.py
+++ b/tests/server/request_handlers/test_default_request_handler.py
@@ -1,4 +1,5 @@
 import asyncio
+import logging
 import time
 
 from unittest.mock import (
@@ -50,6 +51,9 @@
     TextPart,
     UnsupportedOperationError,
 )
+from a2a.utils import (
+    new_task,
+)
 
 
 class DummyAgentExecutor(AgentExecutor):
@@ -579,6 +583,79 @@ async def test_on_message_send_task_id_mismatch():
     assert 'Task ID mismatch' in exc_info.value.error.message  # type: ignore
 
 
+class HelloAgentExecutor(AgentExecutor):
+    async def execute(self, context: RequestContext, event_queue: EventQueue):
+        task = context.current_task
+        if not task:
+            assert context.message is not None, (
+                'A message is required to create a new task'
+            )
+            task = new_task(context.message)  # type: ignore
+            await event_queue.enqueue_event(task)
+        updater = TaskUpdater(event_queue, task.id, task.context_id)
+
+        try:
+            parts = [Part(root=TextPart(text='I am working'))]
+            await updater.update_status(
+                TaskState.working,
+                message=updater.new_agent_message(parts),
+            )
+        except Exception as e:
+            # Stop processing when the event loop is closed
+            logging.warning('Error: %s', e)
+            return
+        await updater.add_artifact(
+            [Part(root=TextPart(text='Hello world!'))],
+            name='conversion_result',
+        )
+        await updater.complete()
+
+    async def cancel(self, context: RequestContext, event_queue: EventQueue):
+        pass
+
+
+@pytest.mark.asyncio
+async def test_on_message_send_non_blocking():
+    task_store = InMemoryTaskStore()
+    push_store = InMemoryPushNotificationConfigStore()
+
+    request_handler = DefaultRequestHandler(
+        agent_executor=HelloAgentExecutor(),
+        task_store=task_store,
+        push_config_store=push_store,
+    )
+    params = MessageSendParams(
+        message=Message(
+            role=Role.user,
+            message_id='msg_push',
+            parts=[Part(root=TextPart(text='Hi'))],
+        ),
+        configuration=MessageSendConfiguration(
+            blocking=False, accepted_output_modes=['text/plain']
+        ),
+    )
+
+    result = await request_handler.on_message_send(
+        params, create_server_call_context()
+    )
+
+    assert result is not None
+    assert isinstance(result, Task)
+    assert result.status.state == TaskState.submitted
+
+    # Polling for 500ms until task is completed.
+    task: Task | None = None
+    for _ in range(5):
+        await asyncio.sleep(0.1)
+        task = await task_store.get(result.id)
+        assert task is not None
+        if task.status.state == TaskState.completed:
+            break
+
+    assert task is not None
+    assert task.status.state == TaskState.completed
+
+
 @pytest.mark.asyncio
 async def test_on_message_send_interrupted_flow():
     """Test on_message_send when flow is interrupted (e.g., auth_required)."""